Whether great powers pursue limited or unlimited power, and what factors lead to their status quo or revisionist policies, are two enduring questions in international relations. Within the school of structural realism, offensive realism and defensive realism have provided starkly different rationales and have depicted entirely distinct international systems and behavioral logics. The study argues that the international system does not consistently favor either balancing or power maximization. Instead, states' behaviors are shaped by their relative power position and perceptions thereof. The paper proposes that security-seeking behavior is a transient phase rather than an immutable principle, challenging traditional defensive realist assumptions. This paper introduces the concept of "Passive Advantage" to explain how states' expectations of power gains influence their strategic choices and to bridge the defensive school and offensive school. The paper applies this framework to analyze Japan's behavior from 1895 to 1937, exploring how passive advantages influenced its transition from constrained policies to expansionism. By introducing the concept of passive advantage, this study offers new insights into great power behavior and provides a novel perspective for understanding historical cases that existing theories struggle to explain. This paper finds that utilizing passive advantages to increase relative power is a crucial pathway for states to transition from security seekers to revisionist states. Additionally, for states possessing significant passive advantages, their war behaviors are closely related to the gains and losses of these passive advantages.